INFLAMMATOEY AFFECTIONS 325 



coronary cushion, the ergots and the chestnuts, but some- 

 times extending to that of the frog and the sole, characterized 

 by a malsecretion of the affected membrane similar to that 

 observed in canker. 



Causes. — The cause which we have indicated for canker — 

 namely, a local specific one, is in all probability the one 

 operating here. Apparently there is a variance of opinion 

 as to whether the condition is actually canker or not. We 

 think, however, that the character of the secretion of the 

 affected membranes, the appearance of the growths, the 

 manner in which they react to the hot iron, the comparative 

 absence of pain, and other points of similarity, point to the 

 fact that the two conditions are actually identical. In other 

 words, the cause is precisely the same, and the only point of 

 difference is the alteration in the point of attack. 



Si/mptoins. — Like canker, the disease is insidious in onset. 

 In precisely similar manner the horn, and in this case the 

 skin of the coronet, is underrun. Later there is the partial 

 shedding and Assuring of the undermined horn and the 

 exuding of the characteristic discharge — in this case not so 

 watery as that of canker. The caseous material of canker 

 is also present, as is a disposition to hypertrophy of the 

 exposed sensitive structures. What horn is left becomes 

 rough and irregularly fissured, and has been likened by 

 some observers to deeply-wrinkled bark of an old tree. A 

 peculiar characteristic of this condition is the state of the 

 ergots and chestnuts. Here the keratogenous membrane 

 participates in the diseased process, and their horn becomes 

 dry and brittle, and readily splits into small fibrous bundles 

 very similar to the fibroid growth described in canker. 

 These excrescences are easily separated from the sensitive 

 structures beneath, and the exposed surface is seen to be 

 more or less moist, or even exhibiting a slight oozing of blood. 



Again, as in canker, the deeper layers of the sensitive 

 structures appear to be normal, the horn-secreting layers 

 being the only ones affected. According to Malcolm, the 

 disease is in its nature equally as inveterate as canker, but 

 it is easier to treat, on account of its more exposed position. 



